PERFUSION OF HUMAN TERM PLACENTA IN SITU WITH C-19 AND C-18 STEROIDS

Abstract

ABSTRACT Five human term placentas were perfused in situ with a combination of dehydroepiandrosterone-7α-3H (DHA-3H) and testosterone-4-14C (T-14C). Five other similar placentas were perfused with dehydroepiandrosterone-7α-3H sulphate (DHAS-3H) and T-14C. Finally three placentas were perfused with 17β-oestradiol-4-14C (OE2-14C). After termination of each of these three perfusions, 17β-oestradiol-6,7-3H (OE2-3H) was administered into the antecubital vein of the mother. The free C-19 compounds (DHA-3H and T-14C) were extensively aromatized; 80% of the material recovered from the placenta, perfusate and urine was in a phenolic form. Identification of this phenolic material from the placenta and perfusate revealed that oestrone (OE1) and 17β-oestradiol (OE2) accounted for 95 % of this. No oestriol (OE3) or ring D phenolic 16-ketols could be detected. The conjugated compound (DHAS-3H) had a pattern of metabolism similar to that of the free compounds but was less extensively utilized. Analysis of the neutral material indicated a virtual absence of placental synthesis and/or release in the foetal circulation of T from DHA and DHAS. The placental metabolism of OE2-14C favoured a preferential release of OE1-14C in the foetal circulation. The 16α-hydroxylation of an 18 carbon steroid could not be detected from the placenta, perfusate or from the material released in the maternal circulation. The absence of 16α-hydroxylase activity in the placenta at term makes it necessary to look into the foetal or maternal compartments for a satisfactory explanation for the rapid rise in the oestriol production at term.